Image capture system, image capturing apparatus, lens unit, control methods therefor, and storage medium

ABSTRACT

An image capturing apparatus is configured to have an interchangeable lens detachably mounted thereto, and is provided with an image capturing unit configured to obtain a captured image, a synchronous signal generation unit configured to generate a synchronous signal for reading out the captured image continuously from the image capturing unit, a communication unit configured to transmit the synchronous signal to the interchangeable lens, and a measurement unit configured to measure a delay time from a timing at which the synchronous signal is generated until a timing at which the communication unit transmits the synchronous signal to the interchangeable lens, the delay time being transmitted to the interchangeable lens by the communication unit together with the synchronous signal.

BACKGROUND OF THE INVENTION

Field of the Invention

The present invention particularly relates to data communication andcontrol of a camera and an interchangeable lens when taking a panningshot, in a camera system that includes the camera and theinterchangeable lens.

Description of the Related Art

A technique called a panning shot is known as a photography techniquethat conveys the feeling of the speed of a moving object. A panning shotaims to make the moving object appear stationary with a flowingbackground, as a result of the user panning the camera in time with themovement of the object. Here, with a panning shot, the user needs to pan(swing the camera) in time with the movement of the object. At thistime, when the panning speed is too fast or too slow, a differenceoccurs between the moving speed of the object and the panning speed,possibly resulting in an image in which the object that the user istrying to stop is blurred. A technology (panning assist) that assiststhe taking of a panning shot has been proposed in response to suchproblems. This panning assist suppresses blurring of the object bymoving a shift lens for image stabilization based on the panning speedof the camera and the motion vector of the object detected from an imageto absorb the difference between the moving speed of the object and thepanning speed.

For example, Japanese Patent Laid-Open No. 2006-317848 proposes a methodthat provides for a successful panning shot, by detecting the differencebetween the moving speed of the object and the speed at which the camerais swung and correcting a shift amount equivalent to the difference inspeed using an image stabilization function.

Also, Japanese Patent Laid-Open No. 2015-161730 proposes a method thatmatches the output timing of a blur detection part with the motionvector of the object image, by changing the output timing of the blurdetection part according to the exposure time or the frame rate, toenhance the detection accuracy of the moving speed of the object.

However, the conventional technologies disclosed in the abovementionedpatent documents are only implementable in an integrated camera in whicha motion vector detection part, an image stabilization control part anda panning assist control part are constituted within the same main body,and consideration is not given to implementation in an interchangeablelens type camera system.

SUMMARY OF THE INVENTION

The present invention has been made in view of the abovementionedproblems, and realizes highly accurate panning assist in aninterchangeable lens type camera system.

According to a first aspect of the present invention, there is providedan image capture system comprising an image capturing apparatus and aninterchangeable lens configured to be detachably mounted to the imagecapturing apparatus, the image capturing apparatus including: an imagecapturing unit configured to obtain a captured image; a synchronoussignal generation unit configured to generate a synchronous signal forreading out the captured image continuously from the image capturingunit; a first communication unit configured to transmit the synchronoussignal to the interchangeable lens; and a first measurement unitconfigured to measure a delay time from a timing at which thesynchronous signal is generated until a timing at which the firstcommunication unit transmits the synchronous signal to theinterchangeable lens, the delay time being transmitted to theinterchangeable lens by the first communication unit together with thesynchronous signal, and the interchangeable lens including: an obtainingunit configured to obtain lens information; a second communication unitconfigured to transmit the lens information to the image capturingapparatus; a receiving unit configured to receive the synchronous signaland the delay time from the image capturing apparatus; a secondmeasurement unit configured to measure a time at which the receivingunit receives the synchronous signal; a calculation unit configured tocalculate a synchronous signal time which is a predicted value of thetiming at which the synchronous signal is generated in the imagecapturing apparatus, by subtracting the delay time from the time,measured by the second measurement unit, at which the synchronous signalis received; and a determination unit configured to determine a timingfor the obtaining unit to obtain the lens information, based on thesynchronous signal time.

According to a second aspect of the present invention, there is providedan image capturing apparatus configured to have an interchangeable lensdetachably mounted thereto, comprising: an image capturing unitconfigured to obtain a captured image; a synchronous signal generationunit configured to generate a synchronous signal for reading out thecaptured image continuously from the image capturing unit; acommunication unit configured to transmit the synchronous signal to theinterchangeable lens; and a measurement unit configured to measure adelay time from a timing at which the synchronous signal is generateduntil a timing at which the communication unit transmits the synchronoussignal to the interchangeable lens, the delay time being transmitted tothe interchangeable lens by the communication unit together with thesynchronous signal.

According to a third aspect of the present invention, there is providedan interchangeable lens configured to be detachably mounted to an imagecapturing apparatus, comprising: an obtaining unit configured to obtainlens information; a communication unit configured to transmit the lensinformation to the image capturing apparatus; a receiving unitconfigured to receive, from the image capturing apparatus, a synchronoussignal and a delay time from generation until communication of thesynchronous signal; a measurement unit configured to measure a time atwhich the receiving unit receives the synchronous signal; a calculationunit configured to calculate a synchronous signal time which is apredicted value of a timing at which the synchronous signal is generatedin the image capturing apparatus, by subtracting the delay time from thetime, measured by the measurement unit, at which the synchronous signalis received; and a determination unit configured to determine a timingfor the obtaining unit to obtain the lens information, based on thesynchronous signal time.

According to a fourth aspect of the present invention, there is provideda method for controlling an image capturing apparatus configured to havean interchangeable lens detachably mounted thereto and including animage capturing unit configured to obtain a captured image, the methodcomprising: generating a synchronous signal for reading out the capturedimage continuously from the image capturing unit; transmitting thesynchronous signal to the interchangeable lens; and measuring a delaytime from a timing at which the synchronous signal is generated until atiming at which the synchronous signal is transmitted to theinterchangeable lens in the transmitting, the delay time beingtransmitted to the interchangeable lens by the transmitting togetherwith the synchronous signal.

According to a fifth aspect of the present invention, there is provideda method for controlling an interchangeable lens configured to bedetachably mounted to an image capturing apparatus, the methodcomprising: obtaining lens information; transmitting the lensinformation to the image capturing apparatus; receiving, from the imagecapturing apparatus, a synchronous signal and a delay time fromgeneration until communication of the synchronous signal; measuring atime at which the synchronous signal is received in the receiving;calculating a synchronous signal time which is a predicted value of atiming at which the synchronous signal is generated in the imagecapturing apparatus, by subtracting the delay time from the time,measured in the measuring, at which the synchronous signal is received;and determining a timing for obtaining the lens information in theobtaining, based on the synchronous signal time.

Further features of the present invention will become apparent from thefollowing description of exemplary embodiments with reference to theattached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram showing the configuration of an imagecapturing apparatus according to a first embodiment of the presentinvention.

FIG. 2 is a flowchart showing image capture synchronous communicationprocessing in the first embodiment.

FIG. 3 is a flowchart showing operations of exposure setting processingin the first embodiment.

FIG. 4 is a flowchart showing operations of exposure processing in thefirst embodiment.

FIG. 5 is a flowchart showing reception processing of synchronous signalcommunication in the first embodiment.

FIG. 6 is a flowchart showing reception processing of angular velocitydetection period setting communication in the first embodiment.

FIG. 7 is a flowchart showing reception processing of object angularvelocity communication in the first embodiment.

FIG. 8 is a flowchart showing reception processing of exposure starttiming communication in the first embodiment.

FIG. 9 is a flowchart showing reception processing of panning assistresult communication in the first embodiment.

FIG. 10 is a timing chart illustrating processing timing of a camerasystem in the first embodiment.

FIG. 11 is a flowchart showing image capture synchronous communicationprocessing in a second embodiment.

FIG. 12 is a flowchart showing reception processing of synchronoussignal communication in the second embodiment.

DESCRIPTION OF THE EMBODIMENTS

Hereinafter, embodiments of the present invention will be described indetail, with reference to the accompanying drawings.

First Embodiment

FIG. 1 is a block diagram showing the configuration of aninterchangeable lens type camera system (image capture system) servingas a first embodiment of an image capturing apparatus of the presentinvention. The interchangeable lens type camera system has a camera mainbody and a detachable interchangeable lens that is communicable with thecamera main body. The configuration of the interchangeable lens typecamera system according to the present embodiment that has a panningassist function will be described, with reference to the block diagramof FIG. 1.

In FIG. 1, a lens unit 200 is detachably mounted to a digital camera 100via a lens mount part 10. First, the configuration of the lens unit 200will be described. The lens unit 200, which is mountable to the digitalcamera 100, includes an image capture optical system that is providedwith a focusing lens 201, a zoom lens 202, a diaphragm 203 and a shiftlens (image stabilization lens) 204. Note that each lens is shown withone lens in FIG. 1, but may be a lens group that is constituted by aplurality of lenses. Light beams incident via the image capture opticalsystem are guided to an image sensor 102, and an image is formed on theimage sensor 102 as an optical image.

Next, the configuration of the digital camera 100 will be described. Ashutter 101 within the digital camera 100 controls light exposure to theimage sensor 102. The image sensor 102, which is constituted by a CCDsensor or a CMOS sensor, converts the optical image of the object intoan analog image signal. Note that the image sensor 102 may have aplurality of focus detection pixels.

An A/D conversion part 103 converts the analog image signal that isoutput from the image sensor 102 into a digital image signal, andoutputs the digital image signal to an image processing part 140 and amemory control part 105. The optical image of the object is observableusing an optical finder 114 via a mirror 112 and a mirror 113, in astate where the mirror 112 is in a down position that is shown inFIG. 1. A timing generation part 104 performs supply (synchronous signalgeneration) of a clock signal and a synchronous signal to the imagesensor 102, the A/D conversion part 103, the image processing part 140,the memory control part 105, and a system control part 130.

The image processing part 140 performs predetermined processing such aspixel interpolation and color conversion on the digital image signalfrom the A/D conversion part 103 or data from the memory control part105, and generates image data. Also, the image processing part 140performs predetermined computational processing using the digital imagesignal. Note that the image processing part 140 is provided with amotion vector detection part 141, and detects the motion vector of acaptured image based on the image data of a plurality of frames that areoutput successively. The computation result of the image processing part140 is input to the system control part 130 via the memory control part105.

The memory control part 105 controls the A/D conversion part 103, thetiming generation part 104, the image processing part 140, a memory 107,a recording part 108, and an image display part 106. The output datafrom the A/D conversion part 103 is written to the memory 107 and therecording part 108, via the image processing part 140 and the memorycontrol part 105.

The memory 107 and the recording part 108 store captured still imagesand moving images. The memory 107 is also used as a workspace of thesystem control part 130. The recording part 108 is used as an imagerecording area that is constituted by a nonvolatile memory attachedinternally or externally. The image display part 106 is constitutedusing an LCD (liquid crystal display) or the like and, in the case of anEVF (electronic view finder), sequentially displays captured image datausing the image display part 106 or an external display device which isnot illustrated, and realizes an EVF function. At the time of imagereproduction, images recorded in the recording part 108 are displayed. Ashutter control part 110 controls the shutter 101 in coordination with amirror control part 111, based on control signals from the systemcontrol part 130. The mirror control part 111 controls the mirror 101,based on control signals from the system control part 130.

The system control part 130 controls various elements of the camera suchas the image sensor 102, the memory control part 105, the shuttercontrol part 110 and the mirror control part 111, in accordance withinput from a shutter switch 115 (SW1), a shutter switch 116 (SW2), acamera operation part 117, the memory control part 105 or the like.Also, the lens unit 200 is controlled via an I/F 120. The entire camerasystem is controlled by these operations.

The shutter switch 115 (SW1) instructs the system control part 130 tostart operations such as AF (autofocus) processing, AE (auto exposure)processing and AWB (auto white balance) processing. The shutter switch116 (SW2) instructs the system control part 130 to start exposure. Thesystem control part 130, having received the exposure start instruction,controls the mirror control part 111, the shutter control part 110, thememory control part 105, and the lens unit 200 via the I/F 120 toexecute processing for recording image data to the recording part 108.

The camera operation part 117 is composed of various buttons, a touchpanel, a power supply ON/OFF button and the like, and outputsinstructions received as a result of user operations to the systemcontrol part 130. In accordance with user operations performed on thecamera operation part 117, the system control part 130 implementsvarious functions installed on the digital camera 100 and switching ofoperation modes such as an AF mode, an AE mode and a panning assistmode.

The camera power supply control part 118 manages an external battery oran internal battery. In the case where the battery has been removed orthe battery has run out, the camera power supply control part 118performs processing for emergency shutdown of camera control. At thistime, the system control part 130 shuts down power supply to the lensunit 200.

An AF control part 131 is installed within the system control part 130,and administers AF processing of the digital camera 100. In AFprocessing, the AF control part 131 calculates the focusing lens driveamount, in accordance with the AF mode, based on lens information suchas focus position (position obtainment) and focal length (focal lengthobtainment) that are obtained from the lens unit 200 via the I/F 120 andAF evaluation values that are input. The focusing lens drive amount isinput to the lens unit 200 via a lens communication control part 133 andthe I/F 120. For example, in the case of a phase difference AF mode, theAF control part 131 causes the optical image of the object to beincident on a focusing state determination part which is not illustratedvia the mirror 112 and a submirror for use in ranging which is notillustrated, and calculates the focusing lens drive amount from phasedifference AF evaluation values or the like that are thus obtained. Inthe case of a contrast AF mode, the AF control part 131 calculates thefocusing lens drive amount from contrast AF evaluation values that arecalculated with the image processing part 140. In the case of an imagecapturing plane phase difference AF mode, the AF control part 131calculates the focusing lens drive amount from image capturing planephase difference AF evaluation values output from pixels for use in AFembedded in the image sensor 102. Also, the AF control part 131 switchesthe AF frame position for calculating AF evaluation values, inaccordance with AF modes such as a one-point AF mode, a multi-point AFmode, and a face detection AF mode.

An AE control part 132 is installed within the system control part 130,and administers AE processing of the digital camera 100. In AEprocessing, the AE control part 132 calculates AE control amounts(diaphragm control amount, shutter control amount, exposure sensitivity,etc.) from lens information such as maximum aperture and focal lengththat is obtained from the lens unit 200 via the I/F 120, AE evaluationvalues that are input and the like, in accordance with the AE mode. Thediaphragm control amount is input to the lens unit 200 via the lenscommunication control part 133 and the I/F 120. The shutter controlamount is input to the shutter control part 110, and exposuresensitivity is input to the image sensor 102. For example, in the caseof a finder photography mode, the AE control amount is calculated fromAE evaluation values that are obtained by causing the optical image ofthe object to be incident on a brightness determination part which isnot illustrated via the mirror 112 and the mirror 113. In the case of alive view photography mode, the AE control part 132 calculates the AEcontrol amount from AE evaluation values that are calculated with theimage processing part 140. Also, the AE control part 132 switches the AEframe position and the weighting amount that are for calculatingevaluation values, in accordance with the light metering mode, whichincludes an evaluation light metering mode, an average light meteringmode and a face detection light metering mode.

A panning assist control part 134 is installed within the system controlpart 130, and administers panning assist processing of the digitalcamera 100. The panning assist function is only executable in the caseof the live view photography mode and where the lens unit 200 that ismounted supports panning assist. If the panning assist function is notexecutable, the panning assist control part 134 notifies the shuttercontrol amount to the AE control part 132 such that the swing angle ofthe object during exposure will be a desired value, based on angularvelocity information of the camera that is obtained from an angularvelocity detection part 208 installed in the lens unit 200, and thelike. Also, only the flow amount of the image is controlled. In the casewhere the panning assist function is executable, the panning assistcontrol part 134 instructs the lens unit 200 via the I/F 120 to executepanning assist processing, in accordance with the panning assist mode.Also, the panning assist control part 134 calculates object angularvelocity information including object angular velocity and objectangular acceleration, from lens information such as focal length andangular velocity information of the camera that is obtained from theangular velocity detection part 208 of the lens unit 200 via the I/F120, the motion vector amount that is input from the image processingpart 140, and the like. Furthermore, the panning assist control part 134calculates the setting value of an angular velocity detection period,from frame rate, shutter speed and the like, such that the angularvelocity detection period (angular velocity obtainment timing) fordetecting the angular velocity at which the digital camera 100 is swungin time with the movement of the object in a panning shot coincides witha motion vector detection period (motion vector detection timing). Theangular velocity information of the object and the setting value of theangular velocity detection period are output to the lens unit 200 viathe lens communication control part 133 and the I/F 120. At this time,the setting value of the angular velocity detection period includesangular velocity ID information. The angular velocity ID information isadded in order for the panning assist control part 134 to determine theperiod in which the angular velocity of the camera that is received fromthe lens unit 200 was obtained. Thus, the angular velocity informationof the camera also includes angular velocity ID information, and thelens unit 200 transmits the angular velocity ID information that wasconveyed with the setting value of the angular velocity detection periodto the digital camera 100 in association with the angular velocityinformation of the camera.

The lens communication control part 133 is installed within the systemcontrol part 130, and administers communication processing between thedigital camera 100 and the lens unit 200. Upon detecting that the lensunit 200 has been mounted via the I/F 120, the digital camera 100 andthe lens unit 200 start communication, and the lens communicationcontrol part 133 performs reception of lens information and transmissionof camera information, drive commands and the like as appropriate. Forexample, in the case of the live view photography mode and where thelens unit 200 that is mounted supports panning assist, the lenscommunication control part 133 implements synchronous signalcommunication. Synchronous signal communication is communication fornotifying, when an image capture synchronous signal is input to thesystem control part 130 from the timing generation part 104, acommunication delay time from the image capture synchronous signal untilcommunication is started. Furthermore, when exposure instructed by theshutter switch 116 (SW2) ends, the system control part 130 receivesinformation on the result of panning assist from the lens unit 200.Also, when the image capture synchronous signal is input from the timinggeneration part 104 in the case of the live view photography mode, thesystem control part 130 collectively receives lens information (focusinglens position, focusing lens state, diaphragm state, focal length,etc.).

The I/F 120 is an interface for the digital camera 100 and the lens unit200 to communicate. Lens information, control commands and the like aretransmitted and received, by implementing communication using electricalsignals between the system control part 130 within the camera and a lenscontrol part 210, via a connector 20.

Next, the configuration of the lens unit 200 will be described. Thefocusing lens 201 moves in the optical axis direction to change thefocus of the image capture optical system. A focus control part 205 iscontrolled by the lens control part 210, and drives the focusing lens201. Also, focus information such as focusing lens position is output tothe lens control part 210.

The zoom lens 202 moves in the optical axis direction to change thefocal length of the image capture optical system. A zoom control part206 is controlled by the lens control part 210, and drives the zoom lens202. Also, zoom information such as focal length is output to the lenscontrol part 210. The diaphragm 203 has a variable opening diameter(aperture value), and changes the amount of light that is incident onthe image sensor 102 as a result of the opening diameter beingcontrolled. A diaphragm control part 207 is controlled by the lenscontrol part 210, and drives the diaphragm 203. Also, apertureinformation such as aperture value is output to the lens control part210.

The shift lens (image stabilization lens) 204 reduces image blur causedby movement of the camera such as camera shake, by moving in a directionorthogonal to the optical axis. The image stabilization control part 209is controlled by the lens control part 210, and drives the shift lens204. Also, image stabilization information such as the range over whichimage stabilization can be implemented is output to the lens controlpart 210. The angular velocity detection part 208 detects the angularvelocity (yaw direction, pitch direction) of the camera, and outputs theangular velocity to the lens control part 210. The angular velocitydetection part 208 is controlled by the lens control part 210.

A lens operation part 211 is composed of a focusing ring, a zoom ring,an AF/MF (autofocus/manual focus) switch, an IS (image stabilization)ON/OFF switch, and the like, and outputs instructions received as aresult of user operations to the lens control part 210. In accordancewith user operations on the lens operation part 211, the lens controlpart 210 executes switching of the operation mode regarding the varioustypes of functions installed in the lens unit 200.

The lens control part 210 controls the entire lens by controlling thefocus control part 205, the zoom control part 206, the diaphragm controlpart 207, the image stabilization control part 209, the angular velocitydetection part 208 and the like, in accordance with input from the lensoperation part 211 and an I/F 220. Also, information input from thevarious control parts, detection parts and the like is transmitted tothe digital camera 100 via the I/F 220, in accordance with the lensinformation obtainment command received from the digital camera 100 withthe I/F 220.

The I/F 220 is an interface for the digital camera 100 and the lens unit200 to communicate, and the system control part 130 within the cameraimplements, via the connector 20, communication using electrical signalsvia the lens communication control part 133. Lens information, controlcommands, and the like are thereby transmitted and received between thedigital camera 100 and the lens unit 200.

Next, FIG. 2 is a flowchart showing operations of synchronous signalcommunication processing of the digital camera 100, in the case of thelive view photography mode and where the lens unit 200 that is mountedsupports panning assist, in the present embodiment. The synchronoussignal communication processing is started when in the live viewphotography mode, and is processing for performing communication for thesystem control part 130 (lens communication control part 133) to notifythe timing of the image capture synchronous signal to the lens unit 200.

In step S201, the system control part 130 determines whether live viewphotography is ongoing. If live view photography is ongoing, theprocessing proceeds to step S202, and if this is not the case, thesynchronous signal communication processing is ended. In step S202, thesystem control part 130 determines whether the image capture synchronoussignal has been input. If the image capture synchronous signal has beeninput, the processing proceeds to step S203, and if this is not thecase, the processing returns to step S201. In step S203, the systemcontrol part 130 stores the time at which the image capture synchronoussignal was input as the synchronous signal time, and the processingproceeds to step S204.

In step S204, the system control part 130 determines whether unprocessedlens communication remains. This unprocessed lens communication is, forexample, communication for notifying the lens drive amount for AF(autofocus) to the lens unit 200. If unprocessed lens communicationremains, the processing proceeds to step S205, and if unprocessed lenscommunication does not remain, the processing proceeds to step S206. Instep S205, the system control part 130 completes the unprocessed lenscommunication, and the processing proceeds to step S206.

In step S206, the system control part 130 determines whether toimplement synchronous signal communication. In the case where the lensunit 200 supports panning assist and the panning assist mode is enabled,the system control part 130 determines to implement synchronous signalcommunication and the processing proceeds to step S207, and if this isnot the case, the processing returns to step S201.

In step S207, the system control part 130 stores the elapsed time frominput of the above synchronous signal time as a communication delay time(delay time measurement), and the processing proceeds to step S208. Instep S208, the system control part 130 implements synchronous signalcommunication to the lens unit 200 via the I/F 120, and the processingproceeds to step S209. In the synchronous signal communication, thecommunication delay time is included as transmission data.

In step S209, the system control part 130 implements communication ofthe setting value of the angular velocity detection period to the lensunit 200 via the I/F 120, and the processing returns to step S201. Inthe communication of the setting value of the angular velocity detectionperiod, the setting value of the angular velocity detection period inputfrom the panning assist control part 134 is transmitted as transmissiondata.

As a result of implementing the above processing, the image capturesynchronous signal can be notified to the lens unit 200 from the digitalcamera 100, and the angular velocity detection period for detecting theangular velocity at which the digital camera 100 is swung can be set.

Next, FIG. 3 is a flowchart showing operations of exposure settingprocessing of the digital camera 100, in the case of the live viewphotography mode and where the lens unit 200 that is mounted supportspanning assist, in the present embodiment. The exposure settingprocessing is started when in the live view photography mode, and isprocessing for controlling the exposure of the next frame.

In step S301, the system control part 130 determines whether live viewphotography is ongoing. If live view photography is ongoing, theprocessing proceeds to step S302, and if this is not the case, theexposure setting processing is ended. In step S302, the system controlpart 130 determines whether the exposure setting timing of the imagesensor for the next frame has arrived. If the exposure setting timinghas arrived, the processing proceeds to step S303, and if this is notthe case, the processing returns to step S301.

In step S303, the system control part 130 performs exposure control ofthe next frame by calculating an exposure setting value based on the AEcontrol amount, the camera mode and the like, and inputting the exposuresetting value to the memory control part 105, and the processingproceeds to step S304.

In step S304, the panning assist control part 134 determines whether toimplement panning assist processing. In the case where the lens unit 200supports panning assist and the panning assist mode is enabled, thepanning assist control part 134 determines to implement panning assistprocessing, and the processing proceeds to step S305, and in the case ofnot implementing panning assist processing, the processing returns tostep S301.

In step S305, the panning assist control part 134 calculates the settingvalue of the angular velocity detection period as a relative time periodfrom input of the image capture synchronous signal, such that the motionvector detection period and the angular velocity detection periodcoincide, based on the exposure setting of the next frame or the like,and the processing proceeds to step S306. The calculated setting valueof the angular velocity detection period is transmitted to the lens unit200 in step S209 of FIG. 2. At this time, the setting value of theangular velocity detection period includes angular velocity IDinformation. The angular velocity ID information is added in order forthe panning assist control part 134 to determine the period in which theangular velocity that is received from the lens unit 200 was obtained.Therefore, angular velocity ID information is included, and the lenscontrol part 210 transmits the angular velocity ID information conveyedwith the setting value of the angular velocity detection period to thedigital camera 100 in association with the angular velocity information.

In step S306, the panning assist control part 134 calculates angularvelocity information of the object including object angular velocity andobject angular acceleration, based on lens information such as focallength and angular velocity information that is received from the lensunit 200, the motion vector amount that is input from the imageprocessing part 140, and the like. After the panning assist control part134 inputs the calculated angular velocity information to the lenscommunication control part 133, the processing proceeds to step S307. Atthis time, in the present embodiment, the obtainment time of the angularvelocity information that is included in the angular velocityinformation used in computation is included in the angular velocityinformation of the object.

In step S307, the lens communication control part 133 implements objectangular velocity communication, in order to transmit the angularvelocity information of the object to the lens unit 200, and theprocessing returns to step S301. At this time, in the presentembodiment, the angular velocity information of the camera is includedin data that is received from the lens unit 200 in the object angularvelocity communication.

Exposure control of the next frame is performed by implementing theabove processing. Also, the angular velocity detection period that isnotified to the lens unit 200 with the next image capture synchronoussignal can be set, and the angular velocity of the object can benotified to the lens unit 200. Also, the angular velocity information ofthe camera can be obtained from the lens unit 200.

Next, FIG. 4 is a flowchart showing operations of live view exposureprocessing of the digital camera 100, in the case of the live viewphotography mode and where the lens unit 200 that is mounted supportspanning assist, in the present embodiment. The live view exposureprocessing is started by an exposure start instruction from the shutterswitch 116 (SW2) when in the live view photography mode.

In S401, the lens communication control part 133 implementscommunication for notifying the lens unit 200 that the exposure starttiming has arrived, and the processing proceeds to step S402. In stepS402, the system control part 130 implements exposure processing inorder to obtain image data, and the processing proceeds to step S403.The image data is recorded to the memory 107 via the image processingpart 140 and the memory control part 105. Note that, in the exposureprocessing of step S402, panning assist is performed automatically, inthe case where the lens unit 200 supports panning assist and the panningassist mode is enabled.

In step S403, the lens communication control part 133 determines whetherpanning assist processing has been implemented in step S402. In the casewhere the lens unit 200 supports panning assist and the panning assistmode is enabled, the lens communication control part 133 determines thatpanning assist processing has been implemented and the processingproceeds to step S405, and if it is determined that panning assistprocessing has not been implemented, the processing proceeds to stepS404. In step S404, the lens communication control part 133 implementscommunication for receiving panning assist result information from thelens unit 200, and the processing proceeds to step S405.

In step S405, the system control part 130 creates EXIF information thatis embedded in the image file, and the processing proceeds to step S406.The EXIF information is recorded to the memory 107 via the memorycontrol part 105. In the present embodiment, the EXIF informationincludes a panning assist result, together with lens information, cameramode and the like. This panning assist result is information such as theobject angular velocity and whether or not the shift lens 204 hasreached the movement boundary.

In step S406, the system control part 130 controls the image processingpart 140 to create an image file from the image data and the EXIFinformation, and record the created image file to the recording part 108via the memory control part 105. By implementing the above processing,the digital camera 100 is able to obtain the result of panning assistimplemented at the time of exposure from the lens unit 200, and torecord the panning assist result in the obtained image data.

Next, FIG. 5 is a flowchart showing reception operations of synchronoussignal communication in the lens unit 200, in the case of the live viewphotography mode and where the lens unit 200 that is mounted supportspanning assist, in the present embodiment. The operations from step S501are started when the lens unit 200 receives synchronous signalcommunication from the digital camera 100.

In step S501, the lens control part 210 stores the time at whichcommunication was implemented by storing the current time of a free-runtimer that is used for time management within the lens unit 200, and theprocessing proceeds to step S502. In step S502, the lens control part210 determines whether communication of the synchronous signal of apredetermined communication data length has been communicated. Ifcommunication is not completed, step S502 is repeated, and whencommunication is completed, the processing proceeds to step S503.

In step S503, the lens control part 210 subtracts the communicationdelay time that is included in the data received in communication of thesynchronous signal from the time at which communication was implemented,which was stored in step S501. Here, the communication delay time is, asalready described, a delay time from the generation timing of the imagecapture synchronous signal by the timing generation part 104 in thedigital camera 100 until the digital camera 100 starts communication. Asa result of the above operation of subtracting the communication delaytime, a timing of the image capture synchronous signal within the lens(predicted value of the timing of the image capture synchronous signalwithin the digital camera 100) that coincides with the timing of theimage capture synchronous signal within the digital camera 100 can becalculated.

Next, FIG. 6 is a flowchart showing reception operations of angularvelocity detection period setting communication in the lens unit 200, inthe case of the live view photography mode and where the lens unit 200that is mounted supports panning assist, in the present embodiment. Theoperations from step S601 are started when the lens unit 200 receivescommunication for setting the angular velocity detection period from thedigital camera 100.

In step S601, the lens control part 210 determines whether communicationfor setting the angular velocity detection period of the camera of apredetermined communication data length has been communicated. Ifcommunication has not been completed, step S601 is repeated, and whencommunication is completed, the processing proceeds to step S602.

In step S602, the lens control part 210 sets (determines) the angularvelocity detection period that is included in the data received in thecommunication for setting the angular velocity detection period of thecamera, and is the period in which the angular velocity of the camera isdetected with reference to the timing of the image capture synchronoussignal within the lens calculated at the aforementioned step S503. Thelens control part 210 obtains the angular velocity in the above angularvelocity detection period from the angular velocity detection part 208,and stores angular velocity information with the angular velocity IDinformation included in communication for setting the angular velocitydetection period and the obtainment time of the angular velocityinformation added thereto. As a result of implementing the aboveprocessing, an angular velocity detection period that coincides with themotion vector detection period in the digital camera 100 can be set inthe lens unit 200.

Next, FIG. 7 is a flowchart showing reception operations of objectangular velocity communication in the lens unit 200, in the case of thelive view photography mode and where the lens unit 200 that is mountedsupports panning assist, in the present embodiment. The operations fromstep S701 are started when the lens unit 200 receives communication ofthe angular velocity of the object from the digital camera 100.

In step S701, the lens control part 210, in order to transmit theangular velocity information of the camera stored in the aforementionedstep S602 to the digital camera 100, readies the angular velocityinformation in a transmission buffer, and the processing proceeds tostep S702. In step S702, the lens control part 210 determines whethercommunication of the angular velocity of the object of a predeterminedcommunication data length has been communicated. If communication hasnot been completed, step S702 is repeated, and when communication iscompleted, the processing proceeds to step S703. In step S703, the lenscontrol part 210 stores the angular velocity information of the objectin preparation for the exposure start timing. As a result ofimplementing the above processing, the lens unit 200 is able to obtainthe angular velocity information of the object from the digital camera100.

Next, FIG. 8 is a flowchart showing reception operations of exposurestart timing communication in the lens unit 200, in the case of the liveview photography mode and where the lens unit 200 that is mountedsupports panning assist, in the present embodiment. The operations fromstep S801 are started when the lens unit 200 receives communication ofthe exposure start timing from the digital camera 100.

In step S801, the lens control part 210 determines whether to performexposure for implementing panning assist processing. If performingexposure for implementing panning assist processing, the processingproceeds to step S802, and if this is not the case, the processingproceeds to step S804. In step S802, the lens control part 210 performsa computational operation for predicting the angular velocity of theobject at the current time, from the angular velocity information of theobject stored in the aforementioned step S703 and the current time, andthe processing proceeds to step S803. For example, in the case where theangular velocity of the object at the current time is given as V, thecurrent time is given as T, the angular velocity of the object that isincluded in the angular velocity information of the object is given asv, the angular acceleration of the object is given as a, and theobtainment time of the angular velocity information of the camera isgiven as t, the lens control part 210 performs the prediction operationusing equation (1) (object angular velocity calculation).

V=v+a×(T−t)  (1)

Note that prediction operation is not limited thereto equation.

In step S803, the lens control part 210 controls the image stabilizationcontrol part 209 using the object angular velocity at the current time,and executes panning assist processing. For example, in the case wherethe correction amount resulting from panning assist is given as G, andthe angular velocity of the camera obtained from the angular velocitydetection part 208 is given as g, the panning assist correction amountis calculated using equation (2).

G=g−V  (2)

Note that the method of computing the correction amount G resulting frompanning assist is not limited thereto equation. By driving the shiftlens 204 by the correction amount resulting from panning assist, itbecomes possible to stop the movement of the object. In step S804, thelens control part 210, rather than performing panning assist, executes anormal image stabilization operation, by performing image stabilizationprocessing using only the angular velocity of the camera obtained fromthe angular velocity detection part 208. As a result of implementing theabove processing, the lens unit 200 is able to execute panning assist atthe time of exposure.

Next, FIG. 9 is a flowchart showing operations for communicating theresult of panning assist, in the case of the live view photography modeand where the lens unit 200 that is mounted supports panning assist, inthe present embodiment. The operations from step S901 are started whenthe lens unit 200 receives communication of the result of panning assistfrom the digital camera 100.

In step S901, the lens control part 210, in order to transmit the objectangular velocity predicted at the aforementioned step S802 and the liketo the digital camera 100 as the result of panning assist, readies theobject angular velocity in a transmission buffer, and the processingproceeds to step S902.

In step S902, the lens control part 210 determines whether communicationof the result of panning assist of a predetermined communication datalength has been communicated. If communication has not been completed,step S902 is repeated, and when communication is completed, theprocessing is completed.

As a result of implementing the above processing, the lens unit 200 isable to obtain an object angular velocity that takes account of the timethat has elapsed from the angular velocity detection time until theexposure start, and perform more highly accurate panning assist.

Next, FIG. 10 is a diagram showing the timing of respective processingduring the panning assist mode, in the case of the live view photographymode and where the lens unit 200 that is mounted supports panningassist, in the present embodiment.

An image capture synchronous signal 1001 is a synchronous signal that isoutput by the timing generation part 104. Image capture accumulation1002 is the accumulation period of the image sensor 102, andaccumulation and readout of electric charges in order from the upperpart of the screen is started on receipt of the image capturesynchronous signal 1001. Synchronous signal communication 1003 is thetiming of synchronous signal communication that is implemented at stepS208 in the synchronous communication processing shown in FIG. 2.

Communication 1004 of the setting value of the detection period of theangular velocity of the camera is the timing of the communication of thesetting value of the detection period of the angular velocity that isimplemented at step S209 in the synchronous communication processing ofFIG. 2. Communication 1005 of the angular velocity of the object is thetiming of the communication of the angular velocity of the objectimplemented at step S307 in the exposure setting processing of FIG. 3.

An angular velocity detection period 1006 is the angular velocitydetection period that is set at step S602 in the processing forcommunicating the setting value of the detection period of the angularvelocity of FIG. 6. When communication of the setting value of theangular velocity detection period ends, the angular velocity of thecamera corresponding to that period is calculated, and the angularvelocity information of the camera is stored with the angular velocityID information that is included in the setting value communication ofthe angular velocity detection period and the obtainment time of angularvelocity information added thereto.

Angular velocity output 1007 is the output from the angular velocitydetection part 208, and the lens control part 210 samples this angularvelocity output during the angular velocity detection period 1006. Forexample, synchronous signal communication 1011 is implemented on receiptof an image capture synchronous signal 1010, and the lens control part210 computes an in-lens image capture synchronous signal timing thatcoincides with the image capture synchronous signal 1010. Thereinafter,due to communication 1012 of the setting value of the angular velocitydetection period being implemented, the detection period setting valueof the angular velocity calculated so as to coincide with a motionvector detection period 1013 in the exposure setting processing of theimmediately previous image capture synchronous signal is transmitted tothe lens unit 200. The lens control part 210 is thereby able to set adetection period 1014 of the angular velocity so as to coincide with themotion vector detection period 1013. Angular velocity information of thecamera obtained due to the detection period 1014 of the angular velocityelapsing is notified to the digital camera 100 by communication 1015 ofthe angular velocity of the object. The panning assist control part 134calculates the angular velocity information of the object from theangular velocity information on the camera at that time and the motionvector information that is obtained in the motion vector detectionperiod 1013. By repeating the above processing, it becomes possible tocontinuously transmit correct angular velocity information of the objectto the lens unit 200.

As described above, according to the present embodiment, the timings ofmotion vector detection and detection of the angular velocity of thecamera can be made to coincide, by implementing synchronous signalcommunication for notifying a communication start delay time to theinterchangeable lens from the camera main body. This enables thedetection accuracy of the moving speed of the object to be raised, andthe accuracy of the panning assist function to be improved.

Second Embodiment

While an image capturing apparatus of a second embodiment of the presentinvention has the same configuration as the first embodiment shown inFIG. 1, the second embodiment realizes an improvement in the performanceof AF control and AE control. The AF control part 131 in FIG. 1 is ableto calculate a more highly accurate focusing lens drive amount, by beingable to correctly grasp the temporal relationship between the AFevaluation value and lens information such as the focusing lensposition, when implementing contrast AF or image capturing plane phasedifference AF. Furthermore, the AE control part 132 is also able tocalculate a more highly accurate AE control amount, by correctlygrasping the temporal relationship between the AE evaluation value andlens information such as the maximum aperture and the focal length.Accordingly, if the digital camera 100 is able to correctly determinethe time at which the lens unit 200 obtains lens information,improvement in the performance of AF control and AE control becomespossible. Thereby, in the second embodiment, a plurality ofcommunications are collectively transmitted, triggered by the imagecapture synchronous signal. Hereinafter, the second embodiment will bedescribed more specifically.

FIG. 11 is a flowchart showing operations of synchronous signalcommunication of the digital camera 100, in the case of the second liveview photography mode and where the lens unit 200 that is mountedsupports panning assist, in the present embodiment. The synchronoussignal communication processing is started when in the live viewphotography mode, and is processing for performing communication for thesystem control part 130 to notify the timing of an image capturesynchronous signal to the lens unit 200.

In step S1101, the system control part 130 determines whether live viewphotography is ongoing. If live view photography is ongoing, theprocessing proceeds to step S1102, and if this is not the case, thesynchronous communication processing is ended. In step S1102, the systemcontrol part 130 determines whether the image capture synchronous signalhas been input. If the image capture synchronous signal has been input,the processing proceeds to step S1103, and if this is not the case, theprocessing returns to step S1101. In step S1103, the system control part130 stores the time at which the image capture synchronous signal wasinput as the image capture synchronous signal timing, and the processingproceeds to step S1104.

In step S1104, the system control part 130 determines whetherunprocessed lens communication remains. This unprocessed lenscommunication is, for example, communication for notifying the lensdrive amount for AF (autofocus) to the lens unit 200. If unprocessedlens communication remains, the processing proceeds to step S1105, andif unprocessed lens communication does not remain, the processingproceeds to step S1106. In step S1105, the system control part 130completes the unprocessed lens communication, and the processingproceeds to step S1106.

In step S1106, the system control part 130 determines whether toimplement synchronous signal communication. In the case where the lensunit 200 supports panning assist and the panning assist mode is enabled,the system control part 130 determines to implement synchronous signalcommunication and the processing proceeds to step S1107, and if this isnot the case, the processing returns to step S1110.

In step S1107, the system control part 130 registers the synchronoussignal communication as communication to be implemented with periodiccommunication which will be discussed later, and the processing proceedsto step S1108. At this time, in the present embodiment, the focusinglens position is included as data received in synchronous signalcommunication. Note that the received data that is included is notlimited thereto. In step S1108, the system control part 130 registersthe communication of the setting value of the angular velocity detectionperiod as communication to be implemented with periodic communicationwhich will be discussed later, and the processing proceeds to stepS1110. In the setting value communication of the angular velocitydetection period, the system control part 130 transits the setting valueof the angular velocity detection period input from the panning assistcontrol part 134, as transmission data.

In step S1109, the system control part 130 registers the communicationfor obtaining the focusing lens position as communication to beimplemented with periodic communication which will be discussed later,and the processing proceeds to step S1110. Note that the communicationthat is registered here is not limited thereto. In step S1110, thesystem control part 130 registers the communication for obtaining theremaining lens information as communication to be implemented withperiodic communication which will be discussed later, and the processingproceeds to step S1111. The registration period is changed, according tothe obtainment frequency that is required for each type of lensinformation.

In step S1111, the lens control part 210 stores the time that haselapsed from the image capture synchronous signal timing until theactual communication as a communication delay time, and the processingproceeds to step S1112. In step S1112, the system control part 130executes the periodic communication (periodic communicationdetermination) registered beforehand with the lens units 200 via the I/F120, and the processing proceeds to step S1101. Note that in the casewhere synchronous signal communication is registered, the delay time ofthe synchronous signal is included as transmission data of thesynchronous signal communication.

As a result of the above processing, the image capture synchronoussignal can be notified to the lens unit 200 from the digital camera 100,the angular velocity detection period can be set, and lens informationof the timing at which the image capture synchronous signal issynchronized can be further obtained.

Next, FIG. 12 is a flowchart showing reception operations of synchronoussignal communication in the lens unit 200, in the case of the live viewphotography mode and where the lens unit 200 that is mounted supportspanning assist, in the present embodiment. The operations from stepS1201 are started when the lens unit 200 first receives synchronoussignal communication from the digital camera 100.

In step S1201, the lens control part 210 stores the time at whichcommunication was implemented, by storing the current time of afree-running timer that is used in time period management within thelens unit 200, and the processing proceeds to step S1202. In step S1202,the lens control part 210, in order to transmit lens information to thedigital camera 100, stores the lens information within a transmissionbuffer, and the processing proceeds to step S1203. At this time, in thepresent embodiment, the focusing lens position is included, astransmission data of the synchronous signal communication.

In step S1203, the lens control part 210 determines whether synchronoussignal communication of a predetermined communication data length hasbeen communicated. If communication has not been completed, step S1203is repeated, and when communication is completed, the processingproceeds to step S1204.

In step S1204, the lens control part 210 calculates an in-lens imagecapture synchronous signal timing that coincides with the image capturesynchronous signal timing within the digital camera 100, by subtracting,from the time, stored in step S1201, at which communication wasimplemented, the delay time from the synchronous signal that is includedin the data received in the synchronous signal communication.

As a result of implementing the above processing, the lens unit 200 isable to determine the in-lens image capture synchronous signal timingthat coincides with the timing of the image capture synchronous signalin the digital camera 100. Also, lens information of the timingsynchronized with an image capture synchronous signal can betransmitted.

As described above, according to the second embodiment, the timings ofmotion vector detection and detection of the angular velocity of thecamera can be made to coincide, by implementing synchronous signalcommunication for notifying a communication start delay time to aninterchangeable lens from the camera main body. Furthermore, the AFevaluation value, the AE evaluation value and the output time period oflens information can be correctly determined. This enables the detectionaccuracy of the moving speed of the object to be raised, and theaccuracy of the panning assist function to be improved. At the sametime, the accuracy of AF control and AE control can be improved.

Other Embodiments

Embodiment(s) of the present invention can also be realized by acomputer of a system or apparatus that reads out and executes computerexecutable instructions (e.g., one or more programs) recorded on astorage medium (which may also be referred to more fully as a‘non-transitory computer-readable storage medium’) to perform thefunctions of one or more of the above-described embodiment(s) and/orthat includes one or more circuits (e.g., application specificintegrated circuit (ASIC)) for performing the functions of one or moreof the above-described embodiment(s), and by a method performed by thecomputer of the system or apparatus by, for example, reading out andexecuting the computer executable instructions from the storage mediumto perform the functions of one or more of the above-describedembodiment(s) and/or controlling the one or more circuits to perform thefunctions of one or more of the above-described embodiment(s). Thecomputer may comprise one or more processors (e.g., central processingpart (CPU), micro processing part (MPU)) and may include a network ofseparate computers or separate processors to read out and execute thecomputer executable instructions. The computer executable instructionsmay be provided to the computer, for example, from a network or thestorage medium. The storage medium may include, for example, one or moreof a hard disk, a random-access memory (RAM), a read only memory (ROM),a storage of distributed computing systems, an optical disk (such as acompact disc (CD), digital versatile disc (DVD), or Blu-ray Disc (BD)™),a flash memory device, a memory card, and the like.

While the present invention has been described with reference toexemplary embodiments, it is to be understood that the invention is notlimited to the disclosed exemplary embodiments. The scope of thefollowing claims is to be accorded the broadest interpretation so as toencompass all such modifications and equivalent structures andfunctions.

This application claims the benefit of Japanese Patent Application No.2016-059153, filed Mar. 23, 2016, which is hereby incorporated byreference herein in its entirety.

What is claimed is:
 1. An image capture system comprising an imagecapturing apparatus and an interchangeable lens configured to bedetachably mounted to the image capturing apparatus, the image capturingapparatus including: an image capturing unit configured to obtain acaptured image; a synchronous signal generation unit configured togenerate a synchronous signal for reading out the captured imagecontinuously from the image capturing unit; a first communication unitconfigured to transmit the synchronous signal to the interchangeablelens; and a first measurement unit configured to measure a delay timefrom a timing at which the synchronous signal is generated until atiming at which the first communication unit transmits the synchronoussignal to the interchangeable lens, the delay time being transmitted tothe interchangeable lens by the first communication unit together withthe synchronous signal, and the interchangeable lens including: anobtaining unit configured to obtain lens information; a secondcommunication unit configured to transmit the lens information to theimage capturing apparatus; a receiving unit configured to receive thesynchronous signal and the delay time from the image capturingapparatus; a second measurement unit configured to measure a time atwhich the receiving unit receives the synchronous signal; a calculationunit configured to calculate a synchronous signal time which is apredicted value of the timing at which the synchronous signal isgenerated in the image capturing apparatus, by subtracting the delaytime from the time, measured by the second measurement unit, at whichthe synchronous signal is received; and a determination unit configuredto determine a timing for the obtaining unit to obtain the lensinformation, based on the synchronous signal time.
 2. The image capturesystem according to claim 1, wherein the interchangeable lens furtherincludes: an angular velocity detection unit configured to obtain anangular velocity at which the image capture system moves, and the lensinformation is the angular velocity.
 3. The image capture systemaccording to claim 2, wherein the image capturing apparatus furtherincludes: a motion vector detection unit configured to detect a motionvector from the captured image read out continuously from the imagecapturing unit; and an angular velocity calculation unit configured tocalculate an angular velocity at which an object moves, based on themotion vector and the angular velocity of the image capture systemobtained by the angular velocity detection unit.
 4. The image capturesystem according to claim 3, wherein the interchangeable lens furtherincludes: an image stabilization unit configured to perform imagestabilization such that the object is stationary on a screen, based onthe angular velocity of the object calculated by the angular velocitycalculation unit and the angular velocity of the image capture systemobtained by the angular velocity detection unit.
 5. The image capturesystem according to claim 4, wherein the image stabilization unit is ashift lens that moves in a direction orthogonal to an optical axis ofthe interchangeable lens.
 6. The image capture system according to claim3, wherein the determination unit determines a timing for the angularvelocity detection unit to obtain the angular velocity, which is thelens information, such that the timing for obtaining the angularvelocity coincides with a timing for detecting the motion vector.
 7. Theimage capture system according to claim 1, wherein the interchangeablelens further includes: a focusing lens; and a position obtaining unitconfigured to obtain a position of the focusing lens, and the lensinformation is information on the position of the focusing lens.
 8. Theimage capture system according to claim 1, wherein the interchangeablelens further includes: a zoom lens; and a focal length obtaining unitconfigured to obtain a focal length of the zoom lens, and the lensinformation is information on the focal length.
 9. The image capturesystem according to claim 1, wherein the image capturing apparatusfurther includes: a periodic communication determination unit configuredto determine, as periodic communication, a plurality of communicationsto be communicated at a timing of the synchronous signal, and the firstcommunication unit sets the synchronous signal communication to abeginning of the periodic communication and implements the periodiccommunication.
 10. An image capturing apparatus configured to have aninterchangeable lens detachably mounted thereto, comprising: an imagecapturing unit configured to obtain a captured image; a synchronoussignal generation unit configured to generate a synchronous signal forreading out the captured image continuously from the image capturingunit; a communication unit configured to transmit the synchronous signalto the interchangeable lens; and a measurement unit configured tomeasure a delay time from a timing at which the synchronous signal isgenerated until a timing at which the communication unit transmits thesynchronous signal to the interchangeable lens, the delay time beingtransmitted to the interchangeable lens by the communication unittogether with the synchronous signal.
 11. An interchangeable lensconfigured to be detachably mounted to an image capturing apparatus,comprising: an obtaining unit configured to obtain lens information; acommunication unit configured to transmit the lens information to theimage capturing apparatus; a receiving unit configured to receive, fromthe image capturing apparatus, a synchronous signal and a delay timefrom generation until communication of the synchronous signal; ameasurement unit configured to measure a time at which the receivingunit receives the synchronous signal; a calculation unit configured tocalculate a synchronous signal time which is a predicted value of atiming at which the synchronous signal is generated in the imagecapturing apparatus, by subtracting the delay time from the time,measured by the measurement unit, at which the synchronous signal isreceived; and a determination unit configured to determine a timing forthe obtaining unit to obtain the lens information, based on thesynchronous signal time.
 12. The interchangeable lens according to claim11, further comprising: a shift lens configured to move in a directionorthogonal to an optical axis of the interchangeable lens.
 13. Theinterchangeable lens according to claim 11, further comprising: anangular velocity detection unit configured to obtain an angular velocityat which the interchangeable lens moves, wherein the lens information isthe angular velocity.
 14. The interchangeable lens according to claim11, further comprising: a focusing lens; and a position obtaining unitconfigured to obtain a position of the focusing lens, wherein the lensinformation is information on the position of the focusing lens.
 15. Theinterchangeable lens according to claim 11, further comprising: a zoomlens; and a focal length obtaining unit configured to obtain a focallength of the zoom lens, wherein the lens information is information onthe focal length.
 16. A method for controlling an image capturingapparatus configured to have an interchangeable lens detachably mountedthereto and including an image capturing unit configured to obtain acaptured image, the method comprising: generating a synchronous signalfor reading out the captured image continuously from the image capturingunit; transmitting the synchronous signal to the interchangeable lens;and measuring a delay time from a timing at which the synchronous signalis generated until a timing at which the synchronous signal istransmitted to the interchangeable lens in the transmitting, the delaytime being transmitted to the interchangeable lens by the transmittingtogether with the synchronous signal.
 17. A method for controlling aninterchangeable lens configured to be detachably mounted to an imagecapturing apparatus, the method comprising: obtaining lens information;transmitting the lens information to the image capturing apparatus;receiving, from the image capturing apparatus, a synchronous signal anda delay time from generation until communication of the synchronoussignal; measuring a time at which the synchronous signal is received inthe receiving; calculating a synchronous signal time which is apredicted value of a timing at which the synchronous signal is generatedin the image capturing apparatus, by subtracting the delay time from thetime, measured in the measuring, at which the synchronous signal isreceived; and determining a timing for obtaining the lens information inthe obtaining, based on the synchronous signal time.
 18. Acomputer-readable storage medium storing a computer program for causinga computer to execute a control method for an image capturing apparatusconfigured to have an interchangeable lens detachably mounted theretoand including an image capturing unit configured to obtain a capturedimage, the control method comprising: generating a synchronous signalfor reading out the captured image continuously from the image capturingunit; transmitting the synchronous signal to the interchangeable lens;and measuring a delay time from a timing at which the synchronous signalis generated until a timing at which the synchronous signal istransmitted to the interchangeable lens in the transmitting, the delaytime being transmitted to the interchangeable lens by the transmittingtogether with the synchronous signal.
 19. A computer-readable storagemedium storing a computer program for causing a computer to execute acontrol method for an interchangeable lens configured to be detachablymounted to an image capturing apparatus, the control method comprising:obtaining lens information; transmitting the lens information to theimage capturing apparatus; receiving, from the image capturingapparatus, a synchronous signal and a delay time from generation untilcommunication of the synchronous signal; measuring a time at which thesynchronous signal is received in the receiving; calculating asynchronous signal time which is a predicted value of a timing at whichthe synchronous signal is generated in the image capturing apparatus, bysubtracting the delay time from the time, measured in the measuring, atwhich the synchronous signal is received; and determining a timing forobtaining the lens information in the obtaining, based on thesynchronous signal time.